1. Field of the Invention
The present invention relates to an optical force sensor to be used to detect an external force.
2. Description of the Related Art
As a force sensor to detect an external force, Japanese Patent Laid-Open No. 2010-281635 discloses one that quantitatively detects the external force from displacement information acquired by using an optical displacement detector that includes multiple light-receiving elements. This optical force sensor is capable of detecting displacements in multiple axes including a displacement in a nonparallel-to-surface direction with respect to light-receiving surfaces of the light-receiving elements while having a small thickness.
However, the force sensor disclosed in Japanese Patent Laid-Open No. 2010-281635 has a difficulty in providing a sufficient sensitivity to detect the displacement in the nonparallel-to-surface direction without reducing its stiffness so as to allow a large displacement in that direction. Furthermore, the disclosed force sensor is likely to be affected by a variation in light quantity of a light source.